title: Influence of biochar on isoproturon partitioning and bioaccessibility in soil.
abstract: The influence of biochar (5%) on the loss, partitioning and bioaccessibility of (14)C-isoproturon ((14)C-IPU) was evaluated. Results indicated that biochar had a dramatic effect upon (14)C-IPU partitioning: (14)C-IPU extractability (0.01 M CaCl2) in biochar-amended treatments was reduced to <2% while, (14)C-IPU extractability in biochar free treatments decreased with ageing from 90% to 40%. A partitioning model was constructed to derive an effective partition coefficient for biochar:water (KBW of 7.82 × 10(4) L kg(-1)). This was two orders of magnitude greater than the apparent Kfoc value of the soil organic carbon:water (631 L kg(-1)). (14)C-radiorespirometry assays indicated high competence of microorganisms to mineralise (14)C-IPU in the absence of biochar (40.3 ± 0.9%). Where biochar was present (14)C-IPU mineralisation never exceeded 2%. These results indicate reduced herbicide bioaccessibility. Increasing IPU application to ×10 its recommended dose was ineffective at redressing IPU sequestration and its low bioaccessibility.
authors.affiliation: School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK. b.reid@uea.ac.uk
authors.forename: B J
authors.initials: BJ
authors.lastname: Reid
authors.forename: F L
authors.initials: FL
authors.lastname: Pickering
authors.forename: A
authors.initials: A
authors.lastname: Freddo
authors.forename: M J
authors.initials: MJ
authors.lastname: Whelan
authors.forename: F
authors.initials: F
authors.lastname: Coulon
mesh_terms: D002606:Charcoal / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D006540:Herbicides / Q000032:analysis / Q000737:chemistry*; D008956:Models, Chemical; D010671:Phenylurea Compounds / Q000032:analysis / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*
chemical_list: D006540:Herbicides; D010671:Phenylurea Compounds; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002606:Charcoal; C028904:isoproturon
keywords: Bioaccessibility; Biochar; Herbicide; Isoproturon; Partition coefficient